Gas turbine engine with integral combustion liner and turbine nozzle

ABSTRACT

A core engine article includes a combustor liner defining a combustion chamber therein and a turbine nozzle. The combustor liner includes a plurality of injector ports, and the plurality of injector ports have a shape that tapers to a corner on a forward side of the injector ports. The turbine nozzle includes a plurality of airfoils. The combustor liner and turbine nozzle are integral with one another. A method of making a core engine article is also disclosed.

BACKGROUND

Attritable or expendable propulsion systems are designed for single-useor only a few uses, as compared to typical flight applications (e.g.,commercial aircraft) that are used repeatedly over hundreds or thousandsof cycles. For example, the propulsion systems may be used to powersmall, unmanned aircraft. Still, the propulsion systems must be reliableand occasionally must exhibit a minimal degree of maintainability.

The attritable or expendable propulsion systems generally include acompressor, a combustor, a turbine, and a turbine nozzle. Thesecomponents each have various subcomponents, such as casings and fluidports

SUMMARY

A core engine article according to an example of the present disclosureincludes a combustor liner defining a combustion chamber therein and aturbine nozzle. The combustor liner includes a plurality of injectorports, and the plurality of injector ports have a shape that tapers to acorner on a forward side of the injector ports. The turbine nozzleincludes a plurality of airfoils. The combustor liner and turbine nozzleare integral with one another.

In a further embodiment according to any of the foregoing embodiments,the plurality of injector ports have a maximum dimension greater thanabout 0.1 in (0.254 cm).

In a further embodiment according to any of the foregoing embodiments,the injector ports are diamond-shaped.

In a further embodiment according to any of the foregoing embodiments, awebbing extends outward from the combustor liner along an extent of aperiphery of the injector ports.

In a further embodiment according to any of the foregoing embodiments,the injector ports extend into the combustion chamber.

In a further embodiment according to any of the foregoing embodiments,the turbine nozzle includes an inner annulus and an outer annulus, theinner annulus extends into the combustion chamber, and the combustorliner is arranged between the inner annulus and the outer annulus.

In a further embodiment according to any of the foregoing embodiments, alip extends from the inner annulus contacts the combustor liner.

In a further embodiment according to any of the foregoing embodiments,the airfoils extend from an exterior of the outer annulus.

In a further embodiment according to any of the foregoing embodiments,an aft end of the combustor liner includes one or more scallops.

A core engine article according to an example of the present disclosureincludes a combustor liner defining a combustion chamber and a turbinenozzle. The combustor chamber includes a plurality of injector ports.The turbine nozzle includes a plurality of airfoils. The airfoils areeach arranged along an airfoil axis, and an angle α between the airfoilaxis and a central axis of the core engine article is greater than about32 degrees. The combustor liner and turbine nozzle are integral with oneanother.

In a further embodiment according to any of the foregoing embodiments,the angle α is about 45 degrees.

In a further embodiment according to any of the foregoing embodiments,the turbine nozzle includes an inner annulus and an outer annulus, theinner annulus extends into the combustion chamber, and the combustorliner is arranged between the inner annulus and the outer annulus.

In a further embodiment according to any of the foregoing embodiments, arib extends from the inner annulus contacts the combustor liner.

In a further embodiment according to any of the foregoing embodiments,the airfoils extend from an exterior of the outer annulus.

In a further embodiment according to any of the foregoing embodiments,an aft end of the combustor liner includes one or more scallops, thescallops are configured to accelerate air flowing through the coreengine article.

A method of making a core engine article according to an example of thepresent disclosure includes depositing material using an additivemanufacturing technique to form a turbine nozzle in a build directionand depositing material using the additive manufacturing technique toform a combustor liner in the build direction. The combustor liner issupported by the turbine nozzle during the build.

In a further embodiment according to any of the foregoing embodiments,forming the combustor liner includes forming a plurality of injectorports, and the injector ports have a maximum dimension greater thanabout 0.1 in (0.254 cm).

In a further embodiment according to any of the foregoing embodiments,the plurality of injector ports have a shape that tapers to a corner ona top side with respect to the build direction.

In a further embodiment according to any of the foregoing embodiments,forming the turbine nozzle includes forming a plurality of airfoils onan outer surface of the turbine nozzle, and the airfoils have anorientation with respect to the build direction such that they areself-supporting during the build.

In a further embodiment according to any of the foregoing embodiments,the airfoils are each built along an airfoil axis, and an angle αbetween the airfoil axis and the build direction is greater than about32 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an attritable/expendable propulsion system.

FIG. 2A schematically shows a core engine article for theattritable/expendable propulsion system of FIG. 1.

FIG. 2B schematically shows a cutaway view of a core engine article ofFIG. 2A.

FIG. 2C schematically shows a turbine nozzle of core engine article ofFIG. 2A.

FIG. 2D schematically shows a detail view of the core engine article ofFIG. 2A.

FIG. 3 schematically shows an additive manufacturing tool.

DETAILED DESCRIPTION

FIG. 1 schematically shows an example attritable/expendable propulsionsystem 10. The propulsion system 10 can be used to power anattritable/expendable aircraft, such as a small unmanned aircraft. Thepropulsion system 10 is designed for single-use or limited-use, butmeets the reliability and maintainability requirements for theparticular application. As an example, an attritable/expendablepropulsion system may have a design life of only a few hours, afterwhich the mission has ended and the propulsion system is renderedinoperable and cannot be recovered/refurbished.

The propulsion system 10 includes a core engine 12, which includes acompressor 14, a combustor 16, and a turbine 18 arranged along a shaft20, which is arranged along central engine axis A. The combustor 16 hasa liner 22 which defines a combustion chamber 24 therein. In general,air is drawn into the compressor 14 for compression and communicationinto the combustion chamber 24 and then expansion through the turbine18. Air exits the turbine via turbine nozzle 26. An outer casing 28surrounds the core engine 12.

In the example of FIGS. 2A-C, the propulsion system 10 includes a coreengine article 30, which is an integral (unitary) structure thatincorporates the combustor liner 22 and turbine nozzle 26. Knowncombustors may include dozens of separate components. In contrast, thepresent core engine article 30 is a single, integral (unitary) pieceformed by additive manufacturing, which is discussed in more detailbelow.

The combustor liner 22 is generally annular in shape and includes aplurality of injector ports 32 through which atomized fuel is injectedinto the combustion chamber 24. The injector ports 32 have a shape andlocation/arrangement that are configured to be fabricated by additivemanufacturing, as is discussed in more detail below. In this example,the injector ports 32 are diamond-shaped. However, other shapes arecontemplated.

The injector ports 32 include a wall 36 that circumscribes an interiorpassage and corresponds to an opening 38. That is, the wall 36 has atubular shape that tracks the circumferential shape of the opening 38.In the example of FIG. 2A-B, the wall 36 has one end that extends intothe combustion chamber 24 to an extent past the inner surface of thecombustor liner 22 and a second end that is flush with an outer wall ofthe combustor liner 22.

A webbing 40 extends outward from the combustor liner 22 along at leasta portion of the periphery of the injector ports 32. The webbing 40 actsas a support for fuel injectors (not shown) which provide the atomizedfuel, and facilitate unimpeded combustion within the combustion chamber24. In the example of FIGS. 2A-B, the webbing 40 extends along less thanthe entire circumference of the injector ports 32.

The combustor liner 22 also includes a plurality of cooling holes 42.The cooling holes 42 can have varying sizes and arrangements around thecombustor liner 22. In the example of FIGS. 2A-B, the cooling holes 42are round and have varying diameters. In other examples, other shapesand diameters can be used.

The turbine nozzle 26 has an inner annulus 44 and an outer annulus 46.An aft end of the combustor liner 22 is interposed between the innerannulus 44 and the outer annulus 46 relative to a central axis A of thepropulsion system 10.

A rib 48 extends circumferentially around an outer surface of the innerannulus 44 at an aft end of the inner annulus 44 (e.g., adjacent ameeting point of the inner annulus 44 and outer annulus 46). The rib 48contacts the combustor liner 22 and sandwiches the combustor liner 22between the rib 48 and outer annulus 46.

An aft end of the liner 22 includes one or more scallop features 50, asbest seen in FIG. 2D. In this example, there are two scallops 50, but inother examples, more or less scallops 50 can be used. The scallops 50are ramps that increase the radius of the outer wall of the combustorliner 22 along the extent of the scallop 50 in the aft direction,towards the meeting point of the inner annulus 44 and the outer annulus46 of the turbine nozzle 26. The ramp shape of the scallops 50accelerates air as it flows past the scallops 50 and into space betweenthe aft end of the combustor liner 22 and the inner annulus 44 in anaftward direction. The acceleration of the air allows it to reversedirections and flows out of the space (in a forward direction) and backinto the combustion chamber 24. Directing air back into the combustionchamber 24 in this manner improves the combustion efficiency of thecombustor 16 because it minimizes air (oxygen) loss.

After flowing through the core engine article 30, air ultimately exitsthe via the turbine nozzle 26. This airflow pattern maximizes combustionefficiency for the propulsion system 10. The scallop features 50 alsocontribute to the structural integrity of the core engine article 30 byproviding reinforcement.

The outer annulus 46 has a plurality of dihedral airfoils 52 arrangedcircumferentially. The dihedral airfoils 52 have a geometry andlocation/arrangement that meets the performance requirements of thepropulsion system 10 and are configured to be fabricated by additivemanufacturing, which is discussed in more detail below. The dihedralairfoils 52 extend along an axis D which is angled with respect to thecentral engine axis A and build direction B.

The core engine article 30 is manufactured by an additive manufacturingtechnique. Additive manufacturing involves building an articlelayer-by-layer from a powder material by consolidating selected portionsof each successive layer of powder until the complete article is formed.For example, the powder is fed into a chamber, which may be under vacuumor inert cover gas. A machine deposits multiple layers of the powderonto one another. An energy beam, such as a laser, selectively heats andconsolidates each layer with reference to a computer-aided design datato form solid structures that relate to a particular cross-section ofthe article. Other layers or portions of layers corresponding tonegative features, such as cavities or openings, are not joined and thusremain as a powdered material. The unjoined powder material may later beremoved using blown air, for example. With the layers built upon oneanother and joined to one another cross-section by cross-section, thearticle is produced. The article may be post-processed to providedesired structural characteristics. For example, the article may be heattreated to produce a desired microstructure. Additive manufacturingprocesses can include, but are not limited to, selective laser melting,direct metal laser sintering, electron beam melting, 3D printing, laserengineered net shaping, or laser powder forming. In this regard, thecore engine article 30 is seamless with regard to distinct boundariesthat would otherwise be formed using techniques such as welding orbrazing. Thus, the (monolithic) core engine article 30, in one example,is free of seams such that there are no distinct boundaries ordiscontinuities in the core engine article 30 that are visually ormicroscopically discernable.

FIG. 3 schematically shows an example additive manufacturing tool 300,such as a laser, which can print a component 302 by any of the additivemanufacturing techniques described above or another additivemanufacturing technique. In the example of FIG. 3, the additivemanufacturing tool 300 is printing the core engine article 30 describedabove, however, the additive manufacturing tool 300 can print any of thestructures described herein.

Additive manufacturing of the core engine article 30 proceeds in a builddirection B as shown in FIGS. 2A-C. In general, relatively complexshapes can be achieved using additive manufacturing. There are, however,limitations. For instance, as an article is being built layer-by-layerin the build direction, the structures that are being built must beself-supporting. Otherwise, the article may break or warp, which mayalso damage the additive manufacturing equipment. As an example,structures that cantilever perpendicularly from the built direction areoften not self-supporting and thus increase the risk of fracture orwarping. In this regard, although the core engine article 30 is anintegration of two functional sections, here the liner 22 and the nozzle26, the configurations of the sections are adapted to be formed byadditive manufacturing, as discussed further below. The core enginearticle 30 thus represents a substantial redesign of the functionalsections to achieve both good performance and manufacturability byadditive manufacturing.

The build direction B is parallel to the central engine axis A. Asshown, the build begins with the turbine nozzle 26 and proceeds to thecombustor liner 22 with injector ports 32. The turbine nozzle 26supports the combustor liner 22 during the build.

As discussed above, the shape and location/arrangement of the injectorports 32 is selected to meet the performance requirements of thepropulsion system. Still, the shape and location/arrangement of theinjector ports 32 are configured to be fabricated by additivemanufacturing. For instance, additive manufacturing techniques can beused to create circular holes in a build piece with diameters up toabout 0.1 inch (0.254 cm). For circular holes greater than about 0.1inch in diameter, a build piece manufactured with additive manufacturingcan exhibit undesirable surface roughness on the top (downward-facing)surface of the hole with respect to the build direction B. Theundesirable surface roughness is related to the angle of curvature thedownward-facing surface with respect to the build direction. For metalpowder bed fusion additive manufacturing techniques there is no solidmetal heat sink below the melt pool when building a hole or opening.Accordingly, the amount of energy supplied to the downward facingsurface and the amount of energy absorbed by the powder are affected.This change in energy can cause surface roughness due to extra materialor lack of material (negative material) of the surrounding geometry, anddepending on the powder size and powder distribution. Roughness requirespost-processing so smooth the surface, because roughness impacts theaerodynamics of airflow past the surface, which can result ininefficiencies and disruptions in the airflow.

On the other hand, hole shapes which taper to a corner on the top(downward-facing) surface of the hole with respect to the builddirection B do not exhibit the surface roughness problem with a maximumdimension larger than 0.1 inches. This is because the angle of curvatureof the downward-facing surface is small enough to avoid the materialmovement/shifting discussed above.

In FIGS. 2A-B, the top, downward-facing surface corresponds to and aftsurface in relation to the propulsion system 10 and axis A. The injectorports 32 have a diamond-shaped geometry wherein the top/aft surface ofthe wall 36 tapers to a corner C1 and the bottom/forward surface of thewall 36 tapers to a corner C2. Another example shape is a teardropshape, with the top surface of the wall tapering to a point and abottom/forward surface of the wall having a rounded shape. In thisexample, the injector ports 32 have a maximum dimension larger than 0.1inches.

As shown in FIG. 2B, the wall 36 has a thickness T that extends betweenan inner and outer surfaces of the wall. The outer surface of the wallmay or may not track the same shape as the inner surface of the wall.For instance, in FIG. 2B, the outer surface of the wall has a morerounded shape than the inner surface of the wall, which has corners C1and C2.

Like the injector ports 32, the dihedral airfoils 52 have a geometrythat is configured to be formed by additive manufacturing. The dihedralairfoils 52 extend along an axis D with respect to the central engineaxis A. During the additive manufacturing build, the dihedral airfoils52 must have enough structural integrity and be arranged with respect tothe body of the turbine nozzle 26 so that they are self-supporting. Ascan be appreciated, the dihedral airfoils 52 extend outward from theturbine nozzle 26 but do not reach the very bottom surface of theturbine nozzle 26 (which corresponds to an aft end of the turbine nozzle26) from which the build proceeds. Accordingly, during the build, thedihedral airfoils 52 extend out from the turbine nozzle 26 withoutsupport. The angle α of the axis D with respect to the central engineaxis A/build direction B is selected to ensure that the dihedralairfoils 52 are self-supporting during the build. If the angle α is toosmall, e.g., the dihedral airfoils 52 are essentially parallel to thecentral engine axis, the dihedral airfoils 52 cannot support themselvesduring the build and can collapse or have imperfections in the materialdeposited by additive manufacturing that can be subject to thermaldistortion during operation of the propulsion system 10. In one example,the angle α is greater than about 32 degrees. In a further example, theangle α is about 45 degrees.

Additive manufacturing of the core engine article 30 allows forunitizing of propulsion system 10 assemblies, integrates complexperformance-enhancing features of the propulsion system 10 with oneanother, lowers production costs, reduces manufacturing and assemblytime/complexity, and allows for quick design changes/iterations whennecessary. These benefits are particularly important toattritable/expendable systems because of the low cost-target andassembly effort requirements.

Furthermore, in this example, the additive manufacturing techniqueallows for the formation of certain small and/or geometrically complexfeatures such as the injector ports 32 and dihedral airfoils 52 thatwould be difficult or impossible to form with a traditional castingprocess.

The foregoing description shall be interpreted as illustrative and notin any limiting sense. A worker of ordinary skill in the art wouldunderstand that certain modifications could come within the scope ofthis disclosure. For these reasons, the following claims should bestudied to determine the true scope and content of this disclosure.

What is claimed is:
 1. A core engine article, comprising: a combustorliner defining a combustion chamber therein, the combustor linerincluding a plurality of injector ports, the plurality of injector portshaving a shape that tapers to a corner on a side of the injector ports;and a turbine nozzle, the turbine nozzle including a plurality ofairfoils, an inner annulus, and an outer annulus, the inner annulusextends into the combustion chamber, and the combustor liner is arrangedbetween the inner annulus and the outer annulus; wherein the combustorliner and turbine nozzle are integral with one another.
 2. The coreengine article of claim 1, wherein the fuel injector ports arediamond-shaped.
 3. The core engine article of claim 1, furthercomprising a webbing extending outward from the combustor liner along anextent of a periphery of the fuel injector ports.
 4. The core enginearticle of claim 3, wherein the webbing is configured to support a fuelinjector.
 5. The core engine article of claim 1, wherein the fuelinjector ports extend into the combustion chamber.
 6. The core enginearticle of claim 1, wherein a rib extending from the inner annuluscontacts the combustor liner.
 7. The core engine article of claim 1,wherein the airfoils extend from an exterior of the outer annulus. 8.The core engine article of claim 1, wherein an end of the combustorliner includes one or more scallops.
 9. The core engine article of claim8, wherein the scallops are configured to accelerate air flowing throughthe core engine article.
 10. The core engine article of claim 8, whereinthe scallops are configured to accelerate airflow through the coreengine article in a direction that is a reverse of the direction of theairflow.
 11. The core engine article of claim 1, wherein the airfoilsare each arranged along an airfoil axis, and an angle α between theairfoil axis and a central axis of the core engine article is 45degrees.
 12. The core engine article of claim 1, wherein each of theplurality of fuel injector ports are configured to receive atomized fuelinto the combustion chamber.
 13. The core engine article of claim 1,wherein the combustion chamber is configured to receive airflow in adirection parallel to a central axis of the core engine article.